User-IRS Association for Sum-Rate Maximization in Multi-IRS Aided Wireless Communication Networks

In this paper, we investigate the assignment of intelligent reflecting surfaces (IRSs) to user-base station (BS) pairs in a multi-IRS-assisted wireless communication network. Our objective is to optimize the allocation of one or more IRSs to each user-BS pair to maximize the overall sum-rate of the network. Using passive beamforming, the transmitted signal is directed towards each user through single or multiple IRSs. To achieve optimal user-IRS allocation, we employ the modified Hungarian algorithm. Additionally, we propose a greedy algorithm for user-IRS association, which offers lower complexity than the modified Hungarian algorithm while still aiming to maximize the sum-rate of the network. Simulation results demonstrate the superiority of modified Hungarian algorithm over other techniques. It has been observed that assigning two IRSs per user-BS pair significantly improves the sum-rate compared to assigning a single IRS per user-BS pair. In particular, with the transmission power of 10 dB and 128 reflection coefficients, the modified Hungarian algorithm achieves a sum-rate improvement of approximately 11.6% compared to the greedy algorithm and 20.6% compared to the random IRS assignment.